| 摘要 |
PROBLEM TO BE SOLVED: To provide a method capable of stably manufacturing a polyester sheet of high quality at a high speed, by closely bringing a molten polyester extruded in a sheetlike shape into contact with a cooling roll having a microcrack surface to solidify the same, while holding the accumulation speed of sublimed matter in the grooves of the microcrack surface to a low level. SOLUTION: The method for manufacturing the polyester sheet allows the molten polyester sheet extruded from an orifice-like cap to fall on the cooling roll having a large number of microcrack passages formed on the surface thereof to bring the same into close contact with the cooling roll, and solidifies the molten polyester film on the cooling roll. The total area Ac (mm<2> ) of the microcrack parts per the surface of 1 mm<2> of the cooling roll coming into contact with the molten polyester sheet is set to a specific range. The temperature difference between the temperature Ti ( deg.C) of cooling water introduced into the cooling roll and the temperature To ( deg.C) of cooling water discharged to the outside of the cooling roll is controlled to a specific range, to continuously form the polyester sheet while preventing the adhesion of the sublimed matter from the polyester sheet to the insides of the microcrak passages of the cooling roll. |
